The present invention generally relates to rearview mirror assemblies for trucks, particularly heavy trucks, as well as coupling alignment warning systems and electronic hitch coupling status-sensing systems.
To couple a vehicle, such as a commercial truck, to a trailer, the driver must continually estimate the position of the vehicle relative to the trailer while maneuvering the vehicle into alignment with the trailer. In practice, this may involve exiting the truck to determine the position of the truck relative to the trailer and then re-entering the truck to maneuver it into alignment. In addition, the driver utilizes his or her rearview side mirrors to approximate the lateral alignment between the truck and trailer, while vertical alignment is often judged only by xe2x80x9cfeel,xe2x80x9d or guess. Such practice often leads to high or low coupling and, possibly, lateral misalignment between the truck and the trailer, which can result in damage to the truck, trailer and/or the interlocking apparatus.
The interlocking apparatus is comprised of components on both the truck and the trailer that mate to achieve a mechanical connection. Typically, the truck is equipped with a locking assembly, known in the heavy trucking industry as a xe2x80x9cfifth wheel hitch,xe2x80x9d and an apparatus mounted to the trailer, known in the industry as a xe2x80x9cking pin.xe2x80x9d The king pin extends downwardly, perpendicular to the bolster plate to which it is attached, the bolster plate being mounted to the bottom surface of the trailer. The fifth wheel hitch includes a hitch plate having a throat with its open end facing rearwardly to receive the king pin, and a locking mechanism for locking the king pin in the throat of the hitch plate.
When backing up the towing unit, the driver often experiences difficulty in aligning the throat of the hitch plate with the king pin. For instance, the height of the king pin relative to the throat may be such that proper mating between the two will not be achieved, even though the two may be laterally aligned. In these instances, the front lower edge of the trailer may crash into the fifth wheel hitch plate (trailer and king pin too low) or the cab of the truck may crash into the body of the trailer (trailer and king pin too high). Alternatively, even though the king pin and fifth wheel hitch may appear coupled, if the king pin is not seated properly in the locking mechanism, a xe2x80x9chigh couplexe2x80x9d may result leading to an unsafe and potentially dangerous condition. On the other hand, even if the two components are at the proper engaging height relative to one another, the throat and the king pin may be laterally misaligned. In either case, positive coupling is not achieved, and the interlocking apparatus and/or the truck/trailer may be damaged or unsafe. Further, the problems attendant with this xe2x80x9cguessworkxe2x80x9d are exacerbated by the fact that the driver will often be faced with zero or low visibility conditions (night, severe weather, sleeper cab configurations, etc.).
As a result, systems have been developed to provide an output signal to the driver indicating the position of the truck relative to the trailer. Notably, known systems are targeted toward the xe2x80x9cball and hitchxe2x80x9d coupling market and are not easily adaptable to the heavy trucking industry.
Known alignment systems use a variety of technologies to measure lateral offset and vertical alignment. Primarily, these systems utilize infrared sensor technology with a modulated pulsed beam. As such, these systems are limited in range (typically less than 20 feet) and require separate sets of infrared sensors on the towing and towed units, respectively, to indicate the lateral offset and vertical alignment. Also, because the infrared emitters and sensors are required on both the towing and towed units, the system must include a remote, powered transmitter on the towed unit. Clearly, these systems are limited in their application, inconvenient, and relatively expensive.
In sum, current commercial truck/trailer coupling is performed relatively xe2x80x9cblindxe2x80x9d because direct observation of the king pin relative to the fifth wheel lock often is not possible. Further, systems such as air-bag suspensions lead to variable trailer and truck height, making positive coupling even more difficult. As a result, the operator relies on external reference points (trailer corner, tires, etc.) to achieve positive coupling. However, such practice often, as described above, leads to missed or incomplete xe2x80x9chard coupling.xe2x80x9d These problems, and the damage often associated therewith, are worsened when the driver is faced with low visibility conditions due to cab design, darkness, weather, etc.
Therefore, the commercial trucking industry is in need of a coupling alignment warning system that is contained in a single, relatively inexpensive unit and which is operational during varying environmental conditions. Such a system would minimize the problems associated with high or low coupling and lateral misalignment that leads to non-positive coupling and, would reduce the damage to the trailer, the truck, the fifth wheel hitch, etc.
Conventionally, fifth wheel hitch type trailer hitches provided no form of feedback to the operator in a driving position that indicates whether the king pin of the trailer was securely positioned within the throat of the hitch plate. Thus, it was necessary for the operators to get out of the cab and visually inspect the hitch to determine whether the king pin was properly positioned in the throat and that the locking mechanism that locks the king pin in place is in a locked and secured position. In an attempt to solve this problem, a proximity sensor was provided to determine when the locking mechanism is in a locked position and a visual indicator was provided in the cab to let the operator know when the trailer was securely coupled to the hitch without requiring the operator to leave the cab. An example of such a system is disclosed in U.S. Pat. No. 5,477,207 issued to Frame, Sr. et al. Despite the additional information that such a system provides to the vehicle operator, the information cannot be relied upon if the electrical system is damaged by a broken or short circuit. Additionally, this system does not provide an operator with other useful information that exists prior to the movement of a locking mechanism into a locked position, such as the proximity of the trailer to the hitch assembly. Further, such a system does not require proper coupling and locking before the truck is driven forward and subsequently driven at high speeds on public roadways.
To overcome these problems, an electronically controlled coupling system was developed by the present assignee and is disclosed in U.S. Pat. No. 5,861,802 issued to Hungerink et al. That patent, however, does not incorporate the features of a coupling alignment warning system, nor does this patent disclose placing the display for the electrically controlled coupling system in a rearview mirror system for the truck in which it is implemented.
According to one embodiment, the truck rearview mirror assembly of the present invention is used on a truck having a coupling status system for sensing trailer coupling status. The rearview mirror assembly includes a mirror housing adapted for mounting to a truck, a mirror disposed within the mirror housing, and a display carried by the housing. The display is coupled to the coupling status system for displaying trailer coupling status information to a driver of the truck.
According to another embodiment, a fifth wheel hitch coupling status sensing system is provided for a truck equipped a fifth wheel hitch and at least one sensor for sensing whether a trailer kingpin is properly locked into the fifth wheel hitch. The system comprises a rearview mirror assembly including a mirror housing, a mirror mounted in the mirror housing, and a support structure adapted for attachment to the exterior of the truck; a display carried on the mirror housing; and a control circuit disposed in the mirror housing and coupled to the display for receiving signals from the at least one sensor and for controlling the display in response to the signals from the sensor to display coupling status information to a driver of the truck.
According to yet another embodiment, an alignment warning system is provided for coupling a towed unit to a towing unit. The system comprises a light source for emitting a beam of light, the light source being attached to the towing unit; at least one sensor attached to the towing unit for receiving light and for generating a detection signal; a control circuit that receives the detection signal and generates an indicator signal in response to the detection signal; and a display mounted in a rearview mirror assembly and responsive to the indicator signal for displaying whether the towing unit is aligned with the towed unit.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.